Issue:
We are using LSR TiWi-R2 module with WL1271 chip. The module performs correctly as WLAN interface under Linux. When we ready signal power level for all access points in the area, thoses the closest show no mor ethan -45 dB level with constant fluctuations to -65db or even -85 dB. These readings are off by -20 dB from other Wifi receivers ( Laptops with Windows) and even when reading with specialized WLAN test software.
We followed teh calibration procedure provided by LSR/TI to no change.
Question:
We would like to read noise power level but full data sheet for this device is not available and we do nto knwo which register may have this value.
Help on both questions will be appreciated
HI,
which WLAN driver are you using? also what commant did you use to measure the Recive Power?
please note that -45dbm is the max power you will see and that is set by SW.
Regards,
Eyal
Thanks for the reply. Do you have information how where to read from the noise power level?
Here are our answers:
We're using kernel 2.6.39 with WL12xx driver (WL1271).
http://linuxwireless.org/en/users/Drivers/wl12xx
To measure received power we're using wpa_supplicant with nl80211 driver
http://wireless.kernel.org/en/users/Documentation/wpa_supplicant
http://wireless.kernel.org/en/developers/Documentation/nl80211
this is the commands we use:
wpa_supplicant -iwlan0 -Dnl80211 -c/etc/wpa_supplicant.conf -B wpa_cli scan wpa_cli scan_results
we tried also
iwlist wlan0 scanning
instead of wpa_supplicant, but the results remained the same and are still unstable and uncorrect.
If we use wext driver (not nl80211):
wpa_supplicant -iwlan0 -Dwext -c/etc/wpa_supplicant.conf -B
we got really strange results with positive received power:
bssid / frequency / signal level / flags / ssid
58:6d:8f:f7:17:ee 2422 211
[WPA-PSK-TKIP][WPA2-PSK-CCMP][ESS] priv_network1
00:24:d1:7a:2e:6e 2412 191
[WPA-PSK-TKIP+CCMP][WPA2-PSK-TKIP+CCMP][ESS] priv_network2
d8:5d:4c:a9:d3:48 2437 175 [WPA2-PSK-CCMP-preauth][ESS]
priv_network4
00:24:d1:78:f4:7f 2412 169
[WPA-PSK-TKIP+CCMP][WPA2-PSK-TKIP+CCMP][ESS] priv_network3
"please note that -45dbm is the max power you will see and that is set by SW"
How can we change this max power limit? Our received power level seems to fluctuate only when network has the real value over that.
Hi,
For WL127x (unlike wl128x) the rssi level is indeed limited by -45dBm.
Which firmware version number is printed when you bring the driver up?
On some previous FW versions, there were some problems with fluctuations.
Best Regards,
Eyal Reizer
We're using wl1271 firmware:
wl1271-fw-2.bin wl1271-fw-ap.bin wl1271-fw.bin wl1271-nvs.bin
Downloaded from:
http://kernel.org/pub/scm/linux/kernel/git/firmware/
When we bring the driver up we receive:
[ 1641.262695] wl1271: down
[ 1641.271179] wl1271: unloaded
[ 1644.848937] wl1271_sdio mmc1:0001:2: wlan0: Features changed:
0x00004800 -> 0x00004000
[ 1644.849517] wl1271: loaded
[ 1644.849517] wl1271: initialized
When you do ifconfig wlan0 up you are expected to see a message indicating that the firmware booted and a print of the fimware version (6.x.x.x)
Anyway for the latest officila TI release (called R5_18) this flunctuation issue should be fixed.
Please refer to the following location for getting a build script which fetches and builds all the components related to this rlease
http://processors.wiki.ti.com/index.php/OMAP_Wireless_Connectivity_mac80211_WLAN_build_scripts
In this link click the "WLAN build Script (R5.00.18)" link which will download the build script zip for you.
You can use this build script for fetching and building all the wlan related components (compat, firmware, hostap, wpa_supplicant...) into your target file system.
Specifically for the firmware you would notice that it is fetched from the following git:
git://github.com/TI-OpenLink/ti-utils.git
under the fimware directory.
Anyway it is better to use all the components from this latest release, so you might better run the script "as is" and let it get all the components for you.
The new driver version works. Now the signal level is stable. Thanks.
Now, we have 3 issues to resolve:
1. Still we have no idea where to read form the noise signal level. We see that other WiFi NIC's provide this info somehow. In digital signal processing domain this could be done by taking FFT of the relevant spectrum and filtering WiFi signals. Since TI does not provide detail data sheet of WL1271 we have no cluse how this could be done.
2. We would like the WL1271 recognize the Access Point radio type b, g, or n. Where to get this information from?
Looking forward to answers to these 2 questions.
George Heston
1. The RSSI range of Wilink6 is between -45dbm to -95dbm. There is no other way to express the energy of WLAN package.
2. You can use "iw wlan0 link" for getting the link information which also indicates whether you are connected to an 11n ap or a legacy b/g ap.
The relevant field is the "tx bitrate:" field.
You can refer to the following link:
http://linuxwireless.org/en/users/Documentation/iw